1. Field of the Invention
The present invention relates to disk devices, in particular disk devices for recording information to/reproducing information from recording medium disks (discs), such as FD (floppy disk) drive devices, CD (compact disc) drive devices, MD (mini disc) drive devices and so forth.
The mini disc is an information recording disc such as that described, for example, in the Japanese journals, Movie Television Technology, 1992/10(482), pages 44-49, `Mini Disc as a Next Generation Audio Media`, written by Tetsuo Yoshida, (Audio Development Group, Sony Corporation, Tokyo), and Television Society Journal, Vol.47, No.6, pages 841-844 (1993), `Newly Developed Technologies for Audio Equipment; Mini Disc` written by Yasuaki Maeda (Audio Development Group, Sony Corporation, Tokyo), and also described in Dig Tech Pap IEEE Int Conf Consum Electron Vol.1993, pages 124-125, `MiniDisc System`, written by Yasuaki Maeda (Audio Development Group, Sony Corporation, Tokyo).
Further, the present invention relates to disk devices which perform a loading operation of drawing a disk cartridge into a holder in response to a part of the disk cartridge being inserted into the holder.
Further, the present invention relates to a disk device which automatically performs a disk loading operation and a disk unloading operation.
Further, the present invention relates to a disk device which holds a disk onto a turntable using a magnetic force.
2. Description of the Related Art
In general in a disk device such as a disc (MD) device, a rotational driving motor, a reading head and so forth are mounted on a frame of the device. In order to cause a media disc (hereinafter, referred to as a `disc`) to enter a reproducible state, it is necessary to convey the disc, held by a disc holder, to a position adjacent to the rotational driving motor, reading head and so forth.
FIGS. 1 and 2 show a lift type disc (MD) device in the related art which will now be described. A collet B (rotational driving motor) for rotating a disc contained in a MD disc cartridge MD and a reading head C for reading information stored in the disc are attached onto a frame A of the device.
A disc holder D for holding the MD disc cartridge MD is placed at a center of a top surface of the frame A. A pair of lift cam plates F.sub.1, F.sub.2 are placed at two sides of the disc holder D, and can move along an MD disc cartridge loading direction as sliding on guiding pins E provided on the top surface of the frame A. The lift cam plates F.sub.1 and F.sub.2 are coupled with each other through an eject plate G extending along a direction perpendicular to the MD disc cartridge loading direction.
In detail, a respective one of force applying springs H are laid between each one of the lift cam plates F.sub.1 and F.sub.2 and the frame A. Due to the force applying springs H, the eject plate G and lift cam plates F.sub.1, F.sub.2 are pulled forward in FIG. 1. A plurality of following pins I are projected from each side wall of the disc holder D and are inserted into lift cams f formed in the lift cam plates F.sub.1 and F.sub.2. Movement of the following pins I are guided by the lift cams f.
Movement preventing nails J are projected from the frame A shown in the figures, and are engaged with some of the following pins I. The engagement prevents the disc holder D from moving along the top surface of the frame A in response to movement of the lift cam plates F.sub.1 and F.sub.2.
In the disc (MD) device, in response to the ejecting plate G being pressed against the pulling force due to the spring H, the lift cam plates F.sub.1 and F.sub.2 fixed to the eject plate G slide together. As a result, due to the function of the lift cams f, the disc holder D is lowered to enter a reproducible state as shown in FIG. 2. In the state, reproduction of information from the disc through the reading head C can be performed.
In the disc (MD) device, the eject plate G is provided between the frame A and the disc holder D. Accordingly, a lift/lower stroke of the disc holder D is elongated, and the disc (MD) device becomes thicker due to the thickness of the eject plate G. Thus, miniaturizing of the disc (MD) device is difficult. Further, the lift cam plates F.sub.1 and F.sub.2 are fixed to the eject plate by spot welding and thus an angular `C`-shaped assembly is obtained. Therefore, it is difficult to ensure that the entire surface is lying in the same plane. It is needed that the assembly is in a plane coincident with a plane of the top surface of the frame A. However, ensuring the entire surface to lie in the same plane in use of the spot welding is difficult and thus the yield of the product is not good.
Recently, use of FD, CD, LD (laser disc), MO (magneto-optical disc), and MD are common when a disk (disc) is used as a recording medium for recording/reproducing information. For example, light and a magnetic field are used for recording information on/reproducing information from the MD. Therefore, an optical head for recording/reproducing, a magnetic head for recording, and various disk driving mechanisms are provided in the disk device.
FIG. 3 shows an exploded structure of a minidisc device in the related art. In the mini-disc device 111, a driving unit 113 is attached inside an enclosure frame 112 and a cover 114 covers the enclosure frame 112.
In the driving unit 113, a loading mechanism having a holder 113b for holding a disc cartridge 115 and a recording/reproducing mechanism having an optical head and a magnetic head for recording/reproducing are provided on a unit frame 113a. The disc cartridge 115 contains, for example, a 2.5-inch magneto-optical disc 115a. A part, extending along a radial direction, of the disc 115a is bared as a result of a shutter 115b sliding in response to the disc cartridge 115 being loaded into the holder 113b.
A front bezel 116 is provided at the front of the enclosure frame 112, and is provided with a disc cartridge 115 inserting hole 116a and an eject button 116b. In the inserting hole 116a, a shutter 117 is provided in a manner in which the shutter 117 can rotate along a disc cartridge 15 inserting direction.
When the disc cartridge 115 is inserted into the inserting hole 116a of the front bezel 116, it is necessary to open the shutter 117 by pressing it and thus the disc cartridge 115 is inserted and thus loaded into the holder 113b of the driving unit 113.
FIGS. 4A and 4B illustrate an operation of the shutter 117 shown in FIG. 3. FIG. 4A shows a state before the disc cartridge 115 is inserted into the inserting hole 116a. In the state, the shutter 117 closes the inserting hole 116a.
When the disc cartridge 115 is inserted into the inserting hole 116a, the shutter 117 is pressed and thus opened. During insertion of the cartridge 115 into the holder 113b, the shutter 117 opened state is maintained as shown in FIG. 4B. When the insertion of the disc cartridge 115 into the holder 113b has been completed, the holder 113b is lowered. Then, the top surface of the rear end of the disc cartridge 115 continues to be in contact with the shutter 117.
When the disc cartridge 115 is ejected from the disc device, the holder 113b is lifted and a predetermined length of the disc cartridge 115 is pressed out from the inserting hole 116a a predetermined distance.
Thus, an opened state of the shutter 117 is maintained as a result of being lifted by the disc cartridge 115 after the disc cartridge 115 has been loaded into the disc device. In this state, the rear end surface of the cartridge 115 closes a part of the inserting hole 116a.
In general, it is understood that it is not likely that optical disc devices such as the above-described mini-disc device, compact disc device and so forth are adversely affected by dirt/dust. Therefore, no special dirt/dust protection is provided therefor.
However, use of a mini-disc device, compact disc device and so forth as an external storing device for a computer or the like has been started. In such a case, differently from a case in which music data is reproduced, an error rate is strictly controlled. If in a mini-disc device, such as the above-described device 111, an opened state of the shutter 117 is maintained as a result of being lifted by the cartridge 115 after the disc cartridge 115 has been loaded into the disc device, as mentioned above, it is likely that dirt/dust will enter through the opened inserting hole 116a. As a result, dirt/dust may adhere to the disc 115a, the optical head, a pickup lens and so forth. Thus, the error rate may be degraded and thus data security may be degraded.
As shown in FIG. 5A, a mini-disc device 301 in the related art is provided with a holder 302 and a drawing mechanism 303. In a mini-disc cartridge 360, a cartridge body 361 contains, as also shown in FIG. 19, a magneto-optical disc 362. A concave portion 366 is formed at a part, near to the inserting-direction forward end, of the right side wall along the inserting direction of the cartridge body 361.
The above-mentioned drawing mechanism 303 has an engaging piece 304 for engaging with the above-mentioned concave portion 366, a slider 305 for supporting the engaging piece 304, a compression spring 306 for pressing the engaging piece 304 along a X.sub.2 direction shown in FIG. 5A and a loading motor 307 for moving the slider 305 along Y.sub.1 and Y.sub.2 directions. The engaging piece 304 is in a state in which the piece 304 projects inside the holder 302.
How the mini-disc cartridge 360 is loaded in the mini-disc device 301 will now be described.
A part of the mini-disc cartridge 360 is inserted into the device 301 manually as follows: An operator inserts the mini-disc cartridge 360 into the holder 302 along the Y.sub.1 direction to enter a state shown in FIG. 5B. At a last step of the insertion, a corner of the cartridge body 361 presses the engaging piece 304 along an X.sub.1 direction. Thus, when the insertion has been completed, the engaging piece 304 is engaged with the concave portion 366 and holds the cartridge 360 due to an elastic force of the compression spring 306, as shown in FIG. 5B.
Then, a drawing operation is performed as follows: When the cartridge 360 has been inserted to enter the state shown in FIG. 5B, the drawing mechanism 303 operates. Specifically, the loading motor 307 is started and rotates forwardly. As a result, the slider 305 slide along the Y.sub.1 direction, and thus the cartridge 360 is drawn into the holder 302 as shown in FIG. 5C. Then, the holder 302 is lowered (is moved along a direction perpendicular to a plane on which FIG. 5C is printed), and thus the cartridge 360 is loaded in the device 301. In this state, recording information on/reproducing information from the disc 362 is performed.
When the cartridge 360 is then unloaded from the device 301, a pressing operation is performed as follows: When an eject button is pressed, the motor 307 is started and rotates reversely. As a result, the holder 302 is lifted and then the slider 305 slides along the Y.sub.2 direction. Thereby a part of the cartridge 360 is pressed out from the holder 302 and thus enters the state shown in FIG. 5B. In this state, the operator may pull out the cartridge 360 from the holder 302 as shown in FIG. 5A by pulling the cartridge 360 along the Y.sub.2 direction.
The above-described disc device 301 has the following problems:
It is likely that the loading operation of the cartridge 360 is unstable. This is because the cartridge 360 is pressed with a force F due to the spring 306 along the X.sub.2 direction after the cartridge 360 has been drawn in the holder 302. As a result, it is likely that the cartridge 360 is inclined so as to rotate in FIGS. 5B and 5C, and thus the loading operation may be not performed smoothly.
Further, the cartridge 360 inserting operation and drawing out operation may require a rather strong force to be applied by the operator. This is because, to achieve each of these operations by the operator's hand, it is necessary to cause the cartridge 360 to press the engaging piece 304 against the elastic force applied by the spring 306. This pressing out operation may require the rather strong force to be applied by the operator.
FIGS. 6A and 6B show a mechanism for loading/unloading of a disc cartridge in a mini-disc device in the related art. FIG. 6A shows a state before the loading is performed (after the unloading has been performed). FIG. 6B shows a state after the loading has been performed.
In a mini-disc cartridge 510 also shown in FIG. 27, a cartridge body 511 contains a magneto-optical disc 512 and has a shutter 513 attached thereto. An iron-made clamp plate 514 is provided to the magneto-optical disc 512 so as to cover a center hole 512a of the disc.
The mini-disc device 520 has a chassis 521, a holder 522, a lift/lower cam plate 523, a turntable 524, a disc motor 525, and a loading motor 526. A permanent magnet 527 is incorporated in the turntable 524. The holder 522 is provided in a manner in which the holder 522 can be lifted and lowered, and the holder 522 has projections 530 and 531 at a side wall. The lift/lower cam plate 523 has inclined cam grooves 532 and 533 therein. The projections 530 and 531 are fitted to the inclined cam grooves 532 and 533, respectively. Each of the inclined cam grooves 532 and 533 has a straight portion extending at an angle .alpha..sub.1 as shown in FIG. 6A.
When the cartridge 310 is inserted into the holder 522, the loading motor 526 is started and rotates forwardly. As a result, as shown in FIG. 6B, the lift/lower plate 523 slides along a Y.sub.1 direction, and thus the holder 522 is lowered along a Z.sub.2 direction to a height H.sub.2 as the projections 530 and 531 are guided by the inclined cam grooves 532 and 533, respectively. The cartridge 510 is lowered together with the holder 522 and thus the cartridge 510 is loaded. The clamp plate 514 of the magneto-optical disc 512 is magnetically attracted by the permanent magnet 527 and thus the disc 512 is loaded on the turntable 524. Thus, the loading of the mini-disc cartridge 510 is completed.
Then, the magneto-optical disc 512 is rotated by the disc motor 525 and then recording information on/reproducing information from the disc 512 is performed.
Then, after the information recording/reproducing has been finished, an ejecting operation may be performed. As a result, the disc motor 525 is stopped, and the loading motor 526 is started and rotates reversely. Thus, the loading motor 526 moves the lift/lower cam plate 523 a predetermined distance l.sub.1 along a Y.sub.2 direction, as shown in FIG. 6A. At this time, the inclined cam grooves 532, 533 guide the projections 530, 531, respectively, and thus the holder 522 is lifted along a Z.sub.1 direction to an original height H.sub.1.
The mini-disc cartridge 510 is lifted together with the holder 522. At this time, the clamp plate 514 is removed from the permanent magnet 527 and thus the magneto-optical disc 512 is removed from the turntable 524. Thus, the unloading of the mini-disc cartridge 510 is completed.
The above-mentioned distance 11 is limited to a predetermined distance in order to miniaturize a depth of the mini-disc device 520. A load borne by the loading motor 526 during the loading operation is approximately uniform.
A load to be borne when the holder 522 is lifted in the unloading operation will now be considered. When the clamp plate 514 is removed from the permanent magnet 527, a load is increased accordingly. After the removal, the load is decreased to be approximately uniform. Further, each of the inclined cam grooves 532, 533 has the straight portion extending at the angle .alpha..sub.1. Therefore, the load to be borne by the loading motor 526 varies in a manner, as indicated by a broken-line curve I shown in FIG. 29, in which the load has a peak value when the magneto-optical disc 512 is removed from the turntable 524.
In order to bear this load, the loading motor 526 has characteristics for generating a torque overcoming the peak load Lmax1 shown in FIG. 29. Such a motor is relatively expensive and has a large size. Accordingly, the mini-disc device 520 is costly and large.
FIG. 7 shows a turntable 610 of a mini-disc device in the related art. The turntable 610 is made from plastic or metal and has a center hub portion 611 and ring-shaped table portion 612. A ring-shaped permanent magnet 613 is fixed in the center hub portion 611. The table portion has a table surface 614 which is a plastic-made or metal-made surface.
In a magneto-optical disc cartridge 620 as shown in FIG. 7, a magneto-optical disc 622 is contained in a cartridge body 621. A center hole 623 is formed in the magneto-optical disc 622 and a central ring portion 624 is provided in the periphery of the center hole 623. Further, a iron-plate-made clamp plate 625 is fixed to the central ring portion 624 so as to cover the center hole 623.
The magneto-optical disc 622 is loaded on the turntable 610 as the center hole 623 is fitted by the center hub portion 611 as indicated by chain double-dashed lines in FIG. 7. In this state, the clamp plate 625 is attracted due to a magnetic force of the permanent magnet 613, and thus the magneto-optical disc 622 is pulled along a direction Z.sub.2 and the central ring portion 624 is pressed on the table surface 614. Due to a static friction force functioning between the central ring portion 624 of the disc 622 and the table surface 614 of the table portion 612, the disc 622 is fixed on the turntable 610.
The central ring portion 624 of the magneto-optical disc 622 is made from synthetic resin, and the table surface 614 is a plastic or metal surface. As a result, a static friction coefficient between the disc 622 and turntable 610 is small. Therefore, it is likely that the disc 622 slides on the turntable 610. If the sliding occurs during a state in which the disc 622 is driven through the turntable 610, a rotation speed of the disc unexpectedly varies and thus normal information recording on/reproducing from the disc 622 cannot be performed. In order to prevent such a situation, a magnetic coercive force of the permanent magnet 613 is large.
A disc device which is currently used for recording/reproducing audio signals may be used as information memory means incorporated in a computer apparatus. However, a disc rotation speed for the information memory means is double or triple than that for the audio signal case. As a result, it is likely that the sliding of the disc on the turntable will occur. Thus, the disc device in the related art may not be suitable for the high rotation speed use.
Further, because the magnetic coercive force of the magnet 613 is large as mentioned above, a relatively strong force is required to remove the disc from the turntable. As a result, a high-power loading motor is needed, and thus miniaturization of the disc device is difficult.